1. Field
The present application relates generally to the operation and design of analog front ends, and more particularly, to the operation and design of area efficient baseband filters.
2. Background
Wireless devices are becoming increasing more complicated and now routinely provide multi-mode and multi-band operation. As a result, efficient utilization of circuit area has become a primary concern. A typical transmitter front end includes a digital-to-analog converter (DAC) to convert digital data to baseband analog signals. Signal conditioning, such as baseband filtering, is used to prepare the baseband analog signals for input to an up-converting mixer. It is desirable to have the signal conditioning utilize as little circuit area as possible while still allowing the transmitter front end to achieve a desired level of signal to noise (SNR) performance.
A typical baseband filter may include an amplifier, a transconductor, and a variety of passive components in a feedback configuration that are used to set the filter response. For example, the filter response may be determined from a product of the resistors and capacitors used in the feedback configuration. Typically, a majority of the circuit area is occupied by the passive elements and the amplifier area, and therefore the circuit area is determined by the number and types of components needed to achieve a desired SNR.
Therefore, it would be desirable to have an improved baseband filter that provides a desired level of noise performance while utilizing less circuit area than conventional baseband filters.